|
Inside
Model M
Example:
P/N 1391401
( Earlier type)
|
Got a junk Model M P/N 1391401 made in 1987.
Condition of upper actuator panel is really
bad but every buckling springs and hammers inside actuators are all
fine. I decided to disassemble the base assembly to pull out
hammers. I also wanted to know if the assembly can be used
again, I mean if it is possible to repair Model M .
|
|
|
All the melted
plastic studs were cut off so that the steel plate can be removed
from the upper actuator panel. |
|
|
|
Membrane sheets are placed like above. |
|
|
|
|
Upper and lower
sheets with conductive tracks are separated by a translucent
membrane sheet which has holes right at the position of each
contacts.
The thickness of the middle translucent sheet gives a gap which
separates contacts on the upper and lower membrane sheets with
signal tracks.
Observing a later model 42H1292, layout of membrane sheets
seems slightly different from 1391401. The most closest membrane
sheet to the actuator panel is directly pressed to the control
PCB. The signal tracks on the lower membrane sheet are also
pressed to the upper membrane sheet and the each signals on the
lower sheet are led to PCB through upper membrane sheet. |
|
|
|
| Actuator panel with hammers is covered with a
rubber sheet. |
Close up of hammers
|
|
|
|
| Hammer units used in this model are translucent
type. Some models use black hammers |
| Comparison ;
Hammer and Actuator of Model F |
|
|
|
|
Hammers used in Model F are larger that those of
Model M.
Every hammers hit the main PCB directly when each keys are
pressed.
The hammer is not a conductive material. You can easily confirm
it using a ohm meter. |
|
Simple spill proof design |
 |
 |
|
There are vinyl tubes at the both
side of upper panel to prevent dusts or liquid. The
upper and lower ends of actuator panel is firmly pressed to the
bottom metal plate by plastic studs ( upper end of studs melted at
the surface of the steel plate and act as "rivets" ) .
A rubber sheet in
between the actuator panel and the steel plate acts as a sealer
and it protect membrane sheets.
Please remind, above two pictures are actuator plate of
1391401. The spill-proof design of a later model such as 42H1292 is
a bit different from
1391401. |
|
|
|
Close up of a stud ( rivet )
there are more than 60 of plastic studs inside the actuator panel. These
studs
act as keys to place membrane sheets and rubber sheet
properly and at the same time each studs is used as a rivet to
press the plate firmly to base steel plate.
In order to re-use the plate after changing hammers or cleaning
membrane sheets, cut off some studs and drill holes
right at the base of each studs.
I did it for my 42H1292 . Do you want to try ?
Well, read this section
|
|
